1. Field of the Invention
This invention relates generally to visual display systems. In particular, this invention relates to a wide angle visual display system for providing a wide angle visual display to trainee pilots, for example the scene from an aircraft.
2. Description of the Prior Art
At present, there are available a wide variety of visual display systems which may be utilized as aircraft training simulators for the viewing of a visual scene by a trainee pilot.
Most such visual display systems of the prior art fall into two general classes, real image display systems in which the trainee pilot directly views a real image projected onto a retroreflective screen or the like, and virtual image display systems in which the trainee pilot looks at a real image through intervening optics which produce a virtual image at optical infinity.
Real image display systems, which include motion picture displays, closed circuit television systems, and the like, simulate the appearance of real world objects by positioning the retroreflective screen, which is utilized to display the real world objects, at a considerable distance from the trainee pilot. However, the aforementioned systems of the prior art ordinarily leave something to be desired in that the real image display systems utilize large size screens, and require considerable light to form the real image on the screen.
Virtual image display systems, which utilize reflective or refractive optics to relay a small real image to the trainee pilot as a large virtual image at optical infinity, overcome the size and brightness disadvantages of real image displays. However, the aforementioned virtual image display systems of the prior art require expensive special purpose optical components to simulate a wide field of view. Further, virtual image display systems tend to be pupil forming, thereby placing restrictions on the position and movement of the trainee pilot's head.